Device for joining flat, thin members that rest against another

ABSTRACT

The system relates to a system for joining flat, relatively thin members that adjoin one another along their narrow face, the members having grooves incorporated into the narrow faces that are parallel to the surface and have groove walls that are parallel to each other, and the joining element being inserted into the grooves of two adjacent members and bridging the partition gap between the members in the manner of an external tongue. In this context the joining element ( 11 ) has, on its part ( 12 ) that can be inserted in the manner of an external tongue in the longitudinal center on its side that faces away from the visible surface of the members, one continuous web or a plurality of aligned webs ( 13 ) that preferably protrude at a right angle, from which detent webs ( 14, 15 ) protrude on both sides, each of which has a detent projection ( 16, 17 ) that projects toward the external-tongue-like part ( 12 ), and on the bottom of the member ( 1, 2 ), which faces away from its visible surface, detent grooves ( 7, 8 ) being provided that run parallel to the adjacent edge at a distance corresponding to the width of the detent webs ( 14, 15 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a system for joining flat, relativelythin members that adjoin one another along their narrow face, themembers having grooves incorporated into the narrow faces that areparallel to the surface and have groove walls that are parallel to eachother, and the joining element being inserted into the grooves of twoadjacent members and bridging the partition gap between the members inthe manner of an external tongue.

[0003] 2. Background Description

[0004] Configurations of this kind have the advantage that all membersare formed completely the same; that is, it is not necessary to ensurethat a side with a groove always faces a side with a tongue, suchmembers also being substantially easier to manufacture. In theinstallation of this known configuration, external tongues are used,whereby the flat member to be attached may be attached without regard toits edge configuration. These known configurations have the disadvantagethat, when installing them, there must be two gluing operations at eachplate abutment because the external tongue has to be anchored with bothlongitudinal edges, namely once on a plate-like member and with theother longitudinal edge in the other member.

[0005] In order to generally avoid gluing at the installation site,disposing detent elements in the area of the tongue-and-groove joint insuch a manner that projections provided on the tongue snap intocorresponding recesses of the groove walls when the flat members thatare to be arranged next to each other are joined is already known.However, in these known designs, especially in those in which the flatjoining elements are formed from the same material as the platesthemselves, one must ensure that the groove walls are elastic enoughthat the front edges of the groove walls in the direction of insertioncan be moved far enough away from each other that the projectionsprovided on the tongue can be moved in between the front edges of thegroove walls without causing damage. In members formed from fiberplates, deficient quality in the fiber plates can in fact cause thegroove walls to break through or break away, causing this member to thenbe unusable. This is especially true if substantial forces are exertedon the groove walls because of a steep inclination of the projectionswhen joining the narrow faces of the members, as is the case, forexample, in European Patent Application Publication no. 813 641.

[0006] Furthermore, providing snap-fit elements made of syntheticmaterial on the back side of the panels whereby the narrow faces of themembers are provided with gradations that engage within each other whenthe plates are fit together was already known. That plate on which theelastic snap-fit element is mounted forms a “groove” together with thestepped wall in which the projection of the step of the adjacent plateis insertable in the manner of a “tongue”. That plate on which the stepto be inserted as a “tongue” is provided has a recess on the back sidein which the snap-fit element of the additional snap-fit organ that isto be fastened to the other plate engages. A design of this type has thedisadvantage, especially with thin plates, that only a little materialis available for clamping the additional snap-fit organ, whereby thestep flanks must absorb the forces that are required to move away thesnap-fit element when joining together the plates. Although it isdescribed within the context of this design that the member to be joinedis swung “tongue-first” into the “groove” on the other member, thisrequires an appropriate amount of play between the step walls that runroughly parallel to the top surface, because otherwise the swinging inis not possible or is possible only when swinging away the snap-fitorgan, which again exerts substantial forces on the steps. A design ofthis type emerges from WIPO patent 94/26999. However, such play permitslimited movement on both sides, which is especially disadvantageous forfloors.

[0007] Furthermore, incorporating tongue-and-groove joints made ofsynthetic material in the edges of the members, for example, by pouringthem in during injection molding or otherwise incorporating them intothe material in order to be able to absorb the spreading forces of thegroove when joining the members, using not a wood-based material, but anelastic material. Such a design emerges from WIPO patent 94/01628, inwhich design the tongue is also slit along its longitudinal centerplane, thereby enabling it to be slightly compressed. Designs of thistype are not usable in terms of manufacturing technology with membersthat are based on wood materials, because in the process wallthicknesses that are too thin may result, which may easily lead to adanger of breakage when joining and also when shipment is not entirelyproper.

SUMMARY OF THE INVENTION

[0008] The object of the present invention is to provide a system of thetype mentioned at the outset with which, on the one hand, a secure jointbetween the two adjacent members is achievable, but the danger ofbreakage and the danger of the members coming apart from each other withuse is prevented.

[0009] According to the invention, this objective is achieved by virtueof the joining element having, on its part that can be inserted in themanner of an external tongue in the longitudinal center on its side thatfaces away from the visible surface of the members, one continuous webor a plurality of aligned webs that preferably protrude at a rightangle, from which detent webs protrude on both sides, each of which hasa detent projection that projects toward the external-tongue-like part,and on the underside of the member, which faces away from its visiblesurface, detent grooves being provided that run parallel to the adjacentedge at a distance corresponding to the width of the detent webs. Inthis way the joining elements that are integrally molded with themembers, or molded in them, are not subjected to bending stress, butonly to compression, because bending only occurs on the joining element,and specifically between the part that can be inserted in the manner ofan external tongue and the associated detent webs, whereas theprojecting area of the member that is to be inserted between these twoparts of the joining element is subject to no bending forces whatsoever,because the groove walls, which have the part that can be inserted inthe manner of an external tongue, run parallel to each other, andbending of the groove cheeks of the members is thus avoided.

[0010] In order to achieve a secure hold between joining element and theassociated members, the delimiting surface of the detent projection thatextends from the detent web may be inclined at an angle equal to orgreater than 85°, preferably 90°-100°, the opposite surface of thedetent groove having the same inclination. With angles greater than 90°there is also a drawing of the area of the member that engages betweenthe external-tongue-like part of the joining element and the detent webinto the joining element when the detent projection(s) is(are) movedinto the detent groove(s). As a result, the groove cheek that faces awayfrom the visible surface can be shorter than the groove cheek that isadjacent to the visible surface by at least about half the thickness ofthe web, thereby achieving, when used in floors for example, a secureadjoining of the areas of the narrow faces that meet at the surface, andthus a tighter surface connection. In order achieve a gentle sliding ofthe detent projections onto the associated part of the member, theinclination of the run-in surface of the detent projections and of theouter edge of the associated groove cheek can be roughly equal. Toproduce a flat foundation, the detent profile that is molded in on thebottom side of the member can be sunken into the bottom by roughly atleast the thickness of the detent webs, thereby causing the member tolie flat against the associated foundation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the drawing, two exemplary embodiments of the subject matterof the invention are shown.

[0012]FIG. 1 diagrammatically shows two members that are joined by meansof the system of the present invention.

[0013]FIG. 2 is a section through two plates in the junction area duringthe attachment of the second plate.

[0014]FIG. 3 depicts the junction area of two plates when the plates arein a joined state.

[0015]FIG. 4 shows a cross-section through a second design variant ofthe joining element.

DETAILED DESCRIPTION OF INVENTION

[0016] The two members are labeled 1 and 2 that are to be joinedside-by-side along their narrow faces 1′, 2′. Members 1, 2 on theirnarrow faces 1′, 2′ have grooves 3, 4 whose lateral flanks run parallelto each other. In the given exemplary embodiment, the lateral surfacesof grooves 3, 4 also run parallel to the top of members 1, 2. Thelateral walls of grooves 3, 4 transition into narrow faces 1′, 2′ viabevels 5 or 6. On the bottom, members 1, 2 have detent grooves 7, 8 thatare provided with run-in surfaces 9, 10, which are disposed runningoutward from narrow faces 1′, 2′ at an angle to the bottom of members 1,2 and transition into detent grooves 7, 8.

[0017] A joining element 11, which has an external-tongue-like part 12that can be inserted into grooves 3, 4 in such a manner as to bridge theinner gap, is provided for joining members 1, 2. The open longitudinaledges of tongue-like part 12 are, as can be seen in the figures, roundedor beveled in order to more easily be introduced along bevels 5, 6 intogrooves 3, 4. The thickness of the external-tongue-like part 12corresponds roughly to the distance of the lateral walls of grooves 3, 4from each other. A junction web 13, at whose bottom end detent webs 14,15 protrude in the front roughly parallel to tongue-like part 12, goesout from external-tongue-like part 12 at a right angle. Detentprojections 16, 17 that project toward tongue-like part 12 are providedon these detent webs and are configured to snap into detent grooves 7,8. The detent projections have wedge surfaces that are inclined in amanner corresponding to the inclination of run-in surfaces 9, 10 andtransition on their back sides into fitting surfaces 14′, 15′, fittingsurfaces 7′, 8′ being provided in the detent grooves against whichfitting surfaces 14′, 15′ of the detent projections come to rest. Due tothe reciprocal support of the fitting surfaces, a latching of thejoining element to adjacent members 1 and 2 is achieved. Because of theinclination of fitting surfaces 7′, 8′ or 14′, 15′, the joining element11 is drawn into the corresponding member when detent projections 14, 15are moved into detent groove 7, 8, which as a further consequence meansthat the members are pulled against each other and narrow faces 1′, 2′are pressed against each other.

[0018] In the design variant according to FIG. 4, undercuts 18, 19,which produce a slight bending resistance of the detent webs when theyare pushed in because of the reduction of the wall thicknesses of thedetent webs, are provided behind fitting surfaces 14′, 15′ in additionto the details on detent webs 14, 15 that have already been described.Also, it is slightly more possible in this way to have a loosening ofthe parts, because, when members 1 and 2 are pulled out from each other,the detent projections around the area of the undercut of the detentwebs can be pivoted, thereby enabling detent projections 16, 17 to bemoved out from detent grooves 7, 8.

[0019] What is essential in the present design is that groove flanks 3′,3″ or 4′, 4″, which are formed by grooves 3, 4, are not subjected tobending stress when external-tongue-like part 12 is pushed in, butinstead the entire bending force or excursion movement of the detentprojections is exerted out on joining element 11, and in particular bythe run-in surface of detent projections 16, 17 running in againstcorresponding run-in surfaces 9, 10 of groove flanks 3′, 4′ and byfacilitating the excursion of the detent webs without an abrupt increasein force during the insertion.

[0020] Depending on the material selected for joining element 11, theholding force can be controlled, specifically, on the one hand, in thatthe individual parts firmly snap together and securely drawing into eachother, whereby a loosening of the parts from each other again can alsobe facilitated. Such a loosening can be achieved or prevented, on theone hand, by the selection of the inclination of fitting surfaces 7′ 8or 14′ 15′, if the angles are less than 90°. Then this results in alatching of the two parts to each other, whereby, when forces act in thedirection of pulling the parts apart, there is a drawing into theassociated detent groove because of reciprocal inclination of the detentprojection.

[0021] The joining element could be formed, in a manner not shown here,in two or more parts, specifically in such a manner that the detent websare fitted on external-tongue-like part 12 or on web 13 as a separateelement, which would have the advantage that, because of the selectionof different materials on the one hand, a rigid external-tongue-likeguide is obtained in the area of external-tongue-like part 12 andgrooves 3, 4, and, on the other hand, a material of high elasticity andstability of shape that poses very little resistance to the joiningtogether of the parts, for example a spring steel or the like, can beused in the area of the detent webs. The wall thickness of the springsteel may also be less than the wall thickness of, for example,external-tongue-like junction web 12.

[0022] As is evident from the present drawing, bottom groove flank 3″ or4″ is slightly shorter than top flank 3′, 4′, which is necessitated bythe fact that face surfaces 1′, 2′ must rest against each other tightlyin order to achieve a tight adjacent placement of the members. However,web 13 is provided in the area of the lower groove flanks 3″, 4″, sothat these groove flanks may be configured to be shorter by half thethickness of web 13. In this way an abutment of the faces of grooveflanks 3″, 4″ against the lateral surfaces of web 13, 14 is ensured,which produces an exceptionally stable joint.

[0023] Furthermore, a formation sunk into the back side of members 1, 2is shown in the drawing, but the hollowed area can be omitted when anunderlayment plate that is bent back appropriately is used, whereuponthere is less of a weakening of bottom groove flank 3″, 4″.

[0024] The features and advantages of the subject matter of theinvention are presented again in summarized form below:

[0025] a) All existing production cylinders may be preserved, becauseabsolutely no geometric alterations to the surface of the member arecalled for,

[0026] b) A simple double profile, which may be made out of PVC,aluminum or similar materials, is used as a joining element and may beproduced in a simple manner by extrusion.

[0027] c) The snapping operation is accomplished using only the returnforce of the joining profile and does not depend on the lateral tensilestrength of the carrier plate.

[0028] d) The strength of the joint may be affected by the height of thedetent projection, the wall thickness of the detent web and by thematerial selected.

[0029] e) The automatic closure of the partition gap between the twomembers and also the strength of the joint can be controlled by theinclination of the fitting surfaces on the detent projection and also onthe detent groove.

[0030] f) The joining element can be pre-mounted on a longitudinal and alateral side during production, specifically by pressing it in using anappropriate device, which makes installation easier.

[0031] g) The members have the same profile on all four sides, therebyachieving a simple manufacture of the members without milling cuttersthat are formed in a complicated manner having to be used.

[0032] h) The flush alignment of the members is produced by theexternal-tongue-like part of the joining element.

[0033] i) The grooves for acceptance of the external-tongue-like partextend at a right angle from the narrow face surfaces and thus parallelto the surfaces of members 1, 2, thereby achieving a precise joining ofthe members.

[0034] j) The detent grooves for the detent projections are placed inthe bottom side of the members and are therefore relatively easy to milland also easy to check.

[0035] k) The joining elements can be milled on four spindles.

[0036] l) Because no tongues are milled on the members, milling cuttersthat correspond in width to the formatting can be used and often can beadjusted in height accordingly.

[0037] The thickness of the members may be varied in accordance with theparticular circumstances or the type of the two members, whereby MDFplates, that is medium thickness fiber plates, may be used in laminatefloors because of the lower stress. With plates of this type, it isnevertheless beneficial to provide at least a thickness of 2.4 mm as alower groove flank, which may be achieved either by increasing theoverall thickness of the member or laminate flooring plate to, forexample, 8 mm or, as already indicated, by selecting the configurationof the detent groove such that the detent webs are not sunken into theplate level.

[0038] While the invention has been described in terms of preferredembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theappended claims.

What is claimed:
 1. A system for joining flat, relatively thin membersthat adjoin one another along their narrow face, the members havinggrooves incorporated into the narrow faces that are parallel to thesurface and have groove walls that are parallel to each other, and thejoining element being inserted into the grooves of two adjacent membersand bridging the partition gap between the members in the manner of anexternal tongue, wherein the joining element (11) has on its part (12)that can be inserted in the manner of an external tongue in thelongitudinal center on its side that faces away from the visible surfaceof the members, one continuous web or a plurality of aligned webs (13)that preferably protrude at a right angle, from which detent webs (14,15) protrude on both sides, each of which has a detent projection (16,17) that projects toward the external-tongue-like part (12), and on theunderside of the member (1,2), which faces away from its visiblesurface, detent grooves (7, 8) being provided that run parallel to theadjacent edge at a distance corresponding to the width of the detentwebs (14, 15).
 2. The system as described in claim 1, wherein thefitting surface (14′, 15′) of the detent projection (16, 17) that goesout from the detent web (14, 15) is inclined at an angle that is equalto or greater than 85°, preferably 90° to 110°, the opposite surface(7′, 8′) of the detent groove (7, 8) having the same inclination.
 3. Thesystem as described in claim 1 or 2, wherein the groove cheek (3″, 4″)that faces away from the visible surface is shorter than the groovecheek (3′, 4′) that is adjacent to the visible surface by approximatelyat least half the thickness of the web (13).
 4. The system as describedin one of claims 1 to 3, wherein the lateral extension of theexternal-tongue like part (12) and that of the detent web (14, 15) areroughly equal.
 5. The system as described in one of claims 1 to 4,wherein the inclination of the run-in surfaces of the detent projections(14, 15) and those of the run-in surfaces (9, 10) of the outside edge ofthe associated groove cheek (3″, 4″) are approximately equal.
 6. Thesystem as described in one of claims 1 to 5, wherein the detent groove(7, 8) that is integrally formed on the bottom of the member (1, 2) issunken into the bottom by approximately at least the thickness of thedetent webs (14, 15).